Life sciences
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Behavioral responses to stressors and the effects of stressors on maternal behavior change with mothering experience. Corticotropin-releasing hormone (CRH) is released by stressors and produces stress-like behavioral effects. We tested the effects of ICV infusion of ovine CRH (0.5-4 ug) on pup-directed behaviors in ovariectomized, ovarian steroid-treated virgin rats that were either naive to pups or that had three days of mothering experience. ⋯ The magnitude and duration of inhibition, especially at the 1 ug dose, were less in rats with mothering experience. Higher doses of CRH (1 - 4 ug) significantly increased pup-killing in rats that were naive to pups. In contrast, CRH produced no pup-killing in rats with mothering experience.
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The changes in hepatic energy state were assessed by 31P-nuclear magnetic resonance spectroscopy (31P-MRS) and arterial ketone body ratio (AKBR) in brain dead dogs. 31P-MRS and AKBR were measured before and at 3 hours after brain death. Wiggers' shock model was employed to compare the energy metabolism during hypotension. 1) The brain death model: Systemic blood pressure changed from 178.3/115.0 mmHg (mean) in the control period, to 259.5/162.5 mmHg during Cushing phenomenon (CU period) and to 63.3/51.7 mmHg after completion of brain death (BD period). beta-ATP/Pi increased from 1.27 +/- 0.14 (mean +/- SEM) to 1.46 +/- 0.16 in the early CU period, and then decreased to 1.11 +/- 0.15 at 60 minutes after BD, followed by a gradual increase to 1.33 +/- 0.13 at 3 hours after BD. Intracellular pH (pHi) increased alkaline to the control value. ⋯ AKBR decreased from 1.00 +/- 0.11 to 0.21 +/- 0.04 in the EX period and increased to 1.08 +/- 0.12 in the RT period. The energy metabolism of the liver was well maintained in the state of brain death in spite of remarkable hypotension, although that was not the case with Wiggers' shock model. It was suggested that the combination of 31P-MRS and AKBR was useful for the evaluation of graft liver viability.